Terahertz transceiver using laser sources

ABSTRACT

A transceiver based on at least one optical source is provided to facilitate wireless communication in a wearable display device, where the wearable display device is embedded with one or more planar antennas. The transceiver operates in terahertz and may be coupled to two different antennas, one for transmission and the other for reception.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to the area of display devicesand particularly relates to architecture and designs of display deviceswith wireless interfaces and wireless transceiver. More particularly,the present invention employs a very-high frequency band (e.g.,terahertz or THz) for a wearable display device to communicate with asource, where an appropriate transceiver is provided to facilitatewireless communication between the display device and the source.

Description of the Related Art

AR (Augmented Reality), VR (Virtual Reality), XR (Extended Reality) andother similar terms are all related to immersive technologies thatenhance or augment the way people perceive and interact with the world,where XR is generally an umbrella term that encompasses both AR and VRor mixed reality (MR), as well as other immersive technologies thatblend the real and virtual worlds. XR enables users to interact withvirtual objects in a physical space. XR is an emerging field with manypotential applications in entertainment, education, healthcare, andmore.

XR (Extended Reality) is typically delivered through a combination ofhardware and software components. The hardware and software worktogether to create a seamless and immersive experience for a user. Theexact delivery method may vary depending on the specific type of XRexperience and the hardware and software being used.

One of the popular delivery methods is via a wearable display device. Awearable display device is a type of electronic device that can be wornon the body and used to display information, images, or video. It can beused for a variety of purposes, including gaming, entertainment,communication, fitness tracking, and more. Wearable display devices canvary in size, shape, and functionality depending on the intended usecase. They typically include a screen or other type of displaytechnology, as well as sensors, processors, and other components neededto provide the desired functionality. To make such a device morewearable, the components on the device are often kept minimum to makethe weight as light as possible.

FIG. 1A shows an exemplary goggle commonly seen in the market for theapplication of delivering or displaying VR or AR. No matter how a goggleis designed, it appears bulky and heavy, and causes inconvenience whenworn on a user. FIG. 1B shows a sketch of HoloLens from Microsoft. Withthe weight being reduced over the years via various design improvement,it remains bulky. A wearer won't feel comfortable when wearing it for aperiod. Indeed.

FIG. 1C shows a type of glasses 100 that can also be used for theapplication of XR or other immersive experience. The glasses 100 appearno significant difference to a pair of normal glasses but include one ortwo flexible cables 102 and 104 that are respectively extended from thetemples 106 and 108. Both of the flexible cables 102 and 104 are coupledat another end thereof to a portable computing device 110, where thecomputing device 110 or external box 110 includes necessary componentsto generate various data to drive a microdisplay in the box 110 or adisplay in the glasses 100. The cable or cables 102 and 104 include aplurality of wires carrying power, control signals and various databetween the box 110 and the glasses 100. The cables 102 and 104,however, inhibit complete free movements of a wearer of the glasses 100.Thus there is a need for solutions of providing a mechanism so that awearer of a wearable display device is not restrained from any movement.

One of the possible mechanisms is to make the communication between awearable display device and a computing device wireless. Traditionalwireless communication (e.g., Wi-Fi or Radio) between these two devices,however, would likely add more components to the wearable displaydevice. Should other types of wireless protocol be used, an appropriatetransceiver must be provided. Thus there is still another need forsolutions that would make the wireless communication feasible withoutadding additional weights on the wearable display glasses.

There are many other needs that are not to be listed individually butcan be readily appreciated by those skilled in the art that these needsare clearly met by one or more embodiments of the present inventiondetailed herein.

SUMMARY OF THE INVENTION

This section is for the purpose of summarizing some aspects of thepresent invention and to briefly introduce some preferred embodiments.Simplifications or omissions in this section as well as in the abstractand the title may be made to avoid obscuring the purpose of thissection, the abstract and the title. Such simplifications or omissionsare not intended to limit the scope of the present invention.

The present invention is generally related to designs of wearabledisplay devices that may be for applications of XR or other immersiveexperience. According to one aspect of the present invention, a wearabledisplay device is made in form of a pair of glasses and includes anantenna layer and a transceiver. The antenna layer includes an antennaarray or a plurality of antenna elements. The antenna layer may bedisposed on top of one or both of integrated lenses in the glasses. Eachof the lenses has a designated display area based on a light waveguide.

According to another aspect of the present invention, the antennaelements are formed in strips in accordance with certain geometry shapesformed to maximize its transceiving efficiency. The thickness, length,width and even turns of the conductive strips as well as the gap betweentwo conductive strips are very well specified to ensure the impedancematching along with the maximized transceiving efficiency including thesensitivity of the antenna and other parameters. Nevertheless, thestrips are small in sizes and often formed via a semiconductor etchingprocess, therefor these antenna elements can be unnoticeable whendisposed on top of a lens.

According to still another aspect of the present invention, the antennaelements may also be disposed over any port of the glasses frameincluding the temples.

According to still another aspect of the present invention, the wearabledisplay device includes a separate balancing unit or balancer to housecircuitry, batteries or etc., where the balancing unit is coupled to theglasses frame via a pair of cables. The balancer is provided tocounteract the weight of the device so that the wearer may feel balancedin weight when wearing the glasses.

According to still another aspect of the present invention, atransceiver based on at least one optical source is provided tofacilitate the wireless communication in the wearable display device.The transceiver operates in terahertz and may be coupled to twodifferent antennas, one for transmission and the other for reception.

The present invention may be implemented as an apparatus, a method, apart of system. Different implementations may yield different benefits,objects and advantages. In one embodiment, the present invention is awearable display device comprising: an eyeglasses frame, at least oneintegrated lens including a light waveguide, a temple attached to theeyeglasses frame, an enclosure integrated on one side of the temple, theenclosure including an image engine generating optical images to projectinto one side of the integrated lens; and an antenna layer, the antennalayer is disposed on top of or distributed over the integrated lens orpart of the eyeglasses frame and the temple, where data is receivedwirelessly in the enclosure via the antenna layer to produce the opticalimages

In another embodiment, the present invention is a wearable displaydevice comprising: an eyeglasses frame, two integrated lensesrespectively framed in the eyeglasses frame, each of the integratedlenses including a light waveguide and a designated viewing area basedon the light waveguide, two temples respectively attached to theeyeglasses frame, each of the temples including an enclosure housing animage engine to generate optical images to project into one side of thelight waveguide; and a balancing unit coupled respectively to the twotemples to counteract a weight of the wearable display device when wornon a user thereof, wherein the balancing unit houses circuitry andbatteries, two antenna layers, each disposed on top of or distributedover one of the integrated lenses or part of the eyeglasses frame andone of the temples, wherein data is received wirelessly in the enclosurevia the balancing unit to produce the optical images.

In yet another embodiment, the present invention is a system foroperating a terahertz transceiver, the system comprises: an antenna set;two optical sources generating two optical beams at two differentfrequencies, a photo mixer for generating or detecting terahertz (THz)radiation, wherein the two optical beams from the optical sources aredirected onto a photoconductive material, a generated terahertz outputsignal is amplified and radiated as the terahertz radiation whenapplying a voltage bias across the photoconductive material. The systemfurther comprises a local oscillator receiving the THz radiation andproduce a reference signal; and an I/O mixer provided to modulate thereference signal with a signal or demodulate the reference signal toextract a signal, wherein the signal is transmitted or received via theantenna set.

There are many other objects, together with the foregoing attained inthe exercise of the invention in the following description and resultingin the embodiment illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1A shows an exemplary goggle now commonly seen in the market forthe application of delivering or displaying VR/AR;

FIG. 1B shows a sketch of HoloLens from Microsoft;

FIG. 1C shows a type of glasses 100 that can also be used for theapplication of XR or other immersive experience;

FIG. 2A shows an overview of an exemplary wearable display device thatmay be used for applications of XR or other immersive experienceaccording to one embodiment of the present invention;

FIG. 2B shows another embodiment in which the control box communicateswith the display device directly via a wireless link;

FIG. 3A shows an exemplary design of a wearable display devicereassembling a pair of glasses with two integrated lenses;

FIG. 3B shows a rear perspective of a wearable display device accordingto one embodiment of the present invention;

FIG. 3C shows an explored view of a temple in a pair of glasses and anenclosure to house optical and electronic parts;

FIG. 3D shows an exemplary design of an integrated lens that may be usedtogether or in an integrated lens;

FIG. 3E shows an embodiment of an antenna layer shown in FIG. 3D. Theantenna layer 354, where the antenna layer includes an antenna or anantenna array;

FIG. 3F shows a perspective view including an exemplary antenna element(e.g., planar antenna) that is disposed on top on a transparentsubstrate (e.g., a piece of glass or a polymer file);

FIG. 3G shows an equivalent circuit to be resonant at a particularfrequency or range of frequencies;

FIG. 3H shows two exemplary charts in accordance with a few exemplaryetch depths (thickness of the antenna strips);

FIG. 31 shows a single piece of glasses (e.g., clip-on or goggle) thatcarries one or more antenna arrays;

FIG. 4A shows an exemplary implementation for an electronic portion thatmay be used in or as part of the control box to provide control signalsand various data to drive an exemplary display device according to oneembodiment of the present invention;

FIG. 4B shows another embodiment in accordance with the presentinvention;

FIG. 4C shows a functional block diagram of an exemplary transceiveraccording to one embodiment of the present invention;

FIG. 4D shows a functional diagram of another terahertz wirelesstransceiver that may be used in smart XR glasses;

FIG. 5A shows an exemplary configuration in which a user is shown towear a wireless display device resembling a pair of reading glasses orsunglasses according to one embodiment of the present invention; and

FIG. 5B shows another embodiment in which the device 504 communicateswith the controller 520 (e.g., iPhone) as well as another controller 522(e.g., Apple Watch).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description of the invention is presented largely in termsof procedures, steps, logic blocks, processing, and other symbolicrepresentations that directly or indirectly resemble the operations ofdata processing devices coupled to networks. These process descriptionsand representations are typically used by those skilled in the art tomost effectively convey the substance of their work to others skilled inthe art.

Reference herein to “one embodiment” or “an embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment can be included in at least one embodiment of theinvention. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment, nor are separate or alternative embodiments mutuallyexclusive of other embodiments. Further, the order of blocks in processflowcharts or diagrams representing one or more embodiments of theinvention do not inherently indicate any particular order nor imply anylimitations in the invention.

Embodiments of the present invention are discussed herein with referenceto FIGS. 2A-5B. However, those skilled in the art will readilyappreciate that the detailed description given herein with respect tothese figures is for explanatory purposes as the invention extendsbeyond these limited embodiments.

Referring now to the drawings, in which like numerals refer to likeparts throughout the several views. FIG. 2A shows an overview 200 of anexemplary wearable display device 202 that may be used for applicationsof XR or other immersive experience according to one embodiment of thepresent invention. The device is designed to appear no significantdifference to a pair of normal glasses but include some extra componentsthat will be further described. One of the advantages, benefits andobjects the device 202 is provided is the wireless communication workingin the band of terahertz or THz.

Radiation in THz, also known as submillimeter radiation, terahertzwaves, has tremendously high frequency. The radiation is often referredto T-rays, T-waves, T-light, T-lux or simply THz, consisting ofelectromagnetic waves within the ITU-designated band of frequencies from0.3 to 3 terahertz (THz), [2] although the upper boundary is somewhatarbitrary and is considered by some sources as 30 THz. One terahertz is1012 Hz or 1000 GHz. Wavelengths of radiation in the terahertz bandcorrespondingly range from 1 mm to 0.1 mm=100 μm. Because terahertzradiation begins at a wavelength of around 1 millimeter and proceedsinto shorter wavelengths, it is sometimes known as the submillimeterband, and its radiation as submillimeter waves, especially in astronomy.This band of electromagnetic radiation lies within the transition regionbetween microwave and far infrared, and can be regarded as either.

According to one embodiment, a computing device or control box 204(e.g., a smart phone) is used to provide control signals and variousdata to an image engine 206 a first wireless link 208. As will bedescribed further below, the image engine 206 is disposed in the glasses202 and receives the signals and data wirelessly. A display screen (notlabeled) in the display device 202 is driven by the image engine 206 viaa second wireless link 210. In this embodiment, both of the first andsecond links 06 and 210 are THz-based wireless. Those skilled in the artthat these components/parts must be equipped with THz-based transceiver.One of the embodiments in the present invention is the design of thetransceiver, which will be further described in detail below whenappropriate.

FIG. 2B shows another embodiment 220 in which the control box 204communicates with the display device 202 directly via a wireless link222. Depending on implementation, the image engine 206 of FIG. 2Adelivers corresponding image/video data to a display in the displaydevice 202 directly, optically or locally without using a wireless link.Unless specifically pointed out, FIG. 2A and FIG. 2B will be referred tointerchangeably when details of the components/parts are describedherein.

Referring now to FIG. 3A, it shows an exemplary design of a wearabledisplay device 300 reassembling a pair of glasses. There are twointegrated lenses 302 and 304. A display area 306 is designated on eachof the integrated lenses 302 and 304. It shall be noted that there is norequirement that each of the lenses 302 and 304 must be designated thedisplay area 306. There may be applications in which only one of thelenses is needed for displaying data/video/image (a.k.a., content).Further the display area 306 is defined as a specific area on a lens fordisplaying the content and may be limited to a certain area of or anentire lens 302 or 304. One each of the lenses 302 and 304, there is anantenna 308. In one embodiment, there are a plurality of antennaembedded in or superimposed on a lens 302 or 304. The antenna 308 isprovided to transceiver (transmit or receive) a wireless signal.

FIG. 3B shows a rear perspective of the device 300 according to oneembodiment of the present invention. The temple 322 includes an extendedtemple 324, shaped substantially similar but expanded and integratedtogether. The extended temple 324 (e.g., in plastic or polycarbonate)provides a conduit to accommodate certain parts (e.g., wires or battery)and form an enclosure 326 near a lens frame 327 to enclose an imageengine.

FIG. 3C shows an explored view of the temple 322 and the enclosure 326to house optical and electronic parts. According to one embodiment,there is an optical cube 328 in the enclosure 326. A microdisplay 329and a light source 330 are attached to the optical cube 328. The lightfrom the light source 330 goes through the cube 328 and is modulated bya displayed image on the microdisplay 329 to form an optical image. Theoptical image is reflected from the microdisplay 329 and impinged uponthe cube 328. A specially designed film or coating 331 in the cube 328redirects the optical image to an optical unit (lens or lenses) 332 thatprojects the optical image into an optical waveguide 234 shown in FIG.3B (representing FIG. 2B). According to another embodiment, the opticalimage is managed to be transmitted to a waveguide in the lens in whichcase the second wireless link is used (representing FIG. 2A). As will befurther described below, the optical waveguide 334 acts as a medium topropagate the image to an appropriate position therein for a wearer toview the optical image.

FIG. 3D shows an exemplary design of an integrated lens 350 that may beused for the lens 302 or 304. The integrated lens 350 may also bereferred to as a waveguide which means that a light beam travels withinthe lens 350. The lens 350 comprises two parts, a glass layer 352 and anantenna layer 354. As the name suggests, the glass layer 352 is largelya waveguide used to transport optical images 356 from an optical lens358 to another end 360, where the optical image can be seen by a wearer(eye) 362.

As described above, one or more microdisplays are used to generate oneor more optical images that are collected by the lens 332 as shown inFIG. 3C. The optical lens 358 (e.g., a collimator) corresponding to thelens 332 projects the image 356 into the waveguide 352. Depending onimplementation, the waveguide 352 may be a stack of one or more piecesof highly transparent materials with different optical characteristicsor glasses coated with one or more films to form a suitable transparentbar for displaying images/videos from a computing device. It is known tothose skilled in the art that an optical waveguide is a spatiallyinhomogeneous structure for guiding light, i.e., for restricting thespatial region in which light can propagate, where a waveguide containsa region of increased refractive index, compared with the surroundingmedium (often called cladding).

The waveguide 352 forms a display area (e.g., corresponding to the area306 of FIG. 3A or the optical waveguide 334 of FIG. 3C). The waveguide352 is transparent and shaped appropriately at one end to allow theimage 356 to be propagated along within the waveguide 334 to the end360, where the user 362 can see through the waveguide 360 so as to seethe propagated image 356 therein. According to one embodiment, one ormore films 364 are disposed upon the waveguide 356 to amplify thepropagated image 356 so that the eye 362 can see a significantlyamplified image 512. One example of such films is what is calledmetalenses, essentially an array of thin titanium dioxide nanofins on aglass substrate. The details of such films are described in U.S. Pat.No. 11,061,179 which is hereby incorporated by reference.

Referring now to FIG. 3E, it shows an embodiment of the antenna layer354 of FIG. 3D. The antenna layer 354 includes an antenna or an antennaarray. An antenna is a device that is used to transmit or receiveelectromagnetic waves. It is usually made of conductive materials, suchas metal, and is designed to be resonant at a particular frequency orrange of frequencies. While FIG. 3E shows an array 370 of five antennaelements 372, it shall be noted that any number of the antenna elements372 is appropriate as long as the impedance thereof matches. Impedancematching is the process of designing the input impedance of an antennaor matching it to the output impedance of corresponding RF circuitry. Ingeneral, the more antenna elements, the more sensitive the array 370 is,thus better reception or transmission. Depending on implementation, thearray 370 may be extended from a small area to a large area on a lensand/or to some or all of the frame that holds the lens, even some or allof one or both of the temples. In one embodiment, the array 370 is madeout of very thin conductive materials on a transparent layercorresponding to the antenna 308 of FIG. 3A.

FIG. 3F shows a perspective view 380 including an exemplary antennaelement 382 (e.g., planar antenna) that is disposed on top on atransparent substrate 384 (e.g., a piece of glass or a polymer file. Inone embodiment, an ITO layer is further deposited on the other side ofthe substrate 384. ITO standing for Indium tin oxide is a ternarycomposition of indium, tin and oxygen in varying proportions. It istransparent and colorless in thin layers.

The element 382 is also shown as a designed or specific geometry shapeformed to maximize its transceiving efficiency. The thickness, length,width and even turns of the conductive strips as well as the gap betweentwo conductive strips are very well specified to ensure the impedancematching along with the maximized transceiving efficiency including thesensitivity of the antenna and other parameters. FIG. 3G shows anequivalent circuit to be resonant at a particular frequency or range offrequencies. According to one embodiment, the parameters W, T, H and Gare redefined or calculated dimensions of the antenna element 382,typically in pm range to resonant at a predefined frequency. In oneembodiment, one or more of these parameters are further tuned to reachthe required resonant frequency (e.g., an optimized THz wave frequencyor 300 GHz). For example, tuning the etch depth “d” of the stipe(equivalent RLC circuit of the planar electric metamaterial antennaelement) can also cause the antenna to be resonant at frequency 300 GHzfor a unique THz wave application. According to one embodiment, theelement 382 or an array of coupled elements substantially similar to theelement 382 are formed through an etching process. FIG. 3H shows twoexemplary charts in accordance with a few exemplary etch depths(thickness of the antenna strips).

FIG. 31 shows a single piece of glasses 390 (e.g., clip-on or goggle)that carries one or more antenna arrays 392. According to oneembodiment, a clip-on single piece 390 is used to provide the XR orimmersive experience. A user may have the freedom to wear a pair ofregular glasses or turn the glasses into a wearable display device byadding the clip-on single piece 390.

As described above, the wearable display device 300 of FIG. 3Acommunicates wirelessly with a control box, where the control boxprovides all control signals and various data. In one embodiment, thewireless communication is conducted in the band of THz. Accordingly, thedevice 300 and the control box must be equipped with at least onetransceiver responsible for enabling the wireless communication.Depending on implementation, the control box may be a specificallydesigned control device or a smart phone. FIG. 4A shows an exemplaryimplementation for the electronic portion 400 that may be used in thecontrol box to provide control signals and various data to drive thedisplay device 300 via two microdisplays 402 and 404 (assuming bothlenses in the device 300 are to display the content), where the twomicrodisplays 402 and 404 are enclosed in an image engine (e.g., theenclosure 326 of FIG. 3B). The details of the electronic portion 400 arecommonly known to those skilled in the art and omitted herein to avoidobscuring aspects of the invention. The electronic portion 400 iscoupled to a transceiver 406 that facilitates the wireless communicationbetween the control box and the device 300, where the device 300includes at least one corresponding transceiver (not shown) coupled tothe image engine.

In operation, the control signals and various data are wirelesslycommunicated between the electronic portion 400 and the image enginethat drives two microdisplays 402 and 404 via two corresponding drivers408 and 410. The wireless communication becomes possible with theantenna described above and at least one of transceivers (e.g., thetransceiver 406).

FIG. 4B shows another embodiment in accordance with the presentinvention. This embodiment enables connectivity between a wiredinterface to a display device. An exemplary wired interface is USBType-C, often referred to as USB-C, being a versatile and widely adoptedconnector standard for connecting various devices and peripherals. Theembodiment is appropriate when a control box (e.g., a smartphone) isalready equipped with a USB-C, where the control box provides allcontrol signals as well as various data. To enable wirelesscommunication in THz band between the control box and display device, aUSB-C to Wireless THz Transceiver (Adapter) 420 is provided to convertall wired signals from a wired interface 422 (e.g., USB-C) into wirelesssignals or vice versa. The wireless signals are received in acorresponding transceiver 424 via an antenna (e.g., antenna array 370),where the transceiver 424 is shown to convert the demodulated signalsback to signals in compliance with the USB-C standard to continue theprocessing of the signals in the electronic portion 400. According toanother embodiment, the demodulated signals may be coupled to theelectronic portion 400 without converting the demodulated signals to theUSB-C signals.

FIG. 4C shows a functional block diagram of a transceiver 430 accordingto one embodiment of the present invention. The transceiver 430 includesthe USB-C conversation circuit 432. Those skilled in the art canappreciate that the transceiver 430 can be simply modified toaccommodate other signals from other interfaces (e.g., Bluetooth orWi-Fi) in view of the description herein. The transceiver 430 includes atransmission portion 434 and a receiving portion 436. When one or moresignals are received from an interface (e.g., the USB-C interface 432),the signals are modulated in a modulator 438 that produces twocomponents: the in-phase (I) component and the quadrature (Q) component.Essentially in the context of quadrature modulation schemes, such asQuadrature Amplitude Modulation (QAM), the modulated signal includesthese two components: the I component and the Q component. The Icomponent represents the real part of the modulated signal, and the Qcomponent represents the imaginary part of the modulated signal.Together, these components convey both the amplitude and phaseinformation of the modulated signal.

In one embodiment, the I and Q components are derived by using atechnique called quadrature demodulation, which involves mixing themodulated signal with two local oscillator signals that are 90 degreesout of phase with each other. The resulting signals after mixing are theI and Q components. By having two separate components, the modulatedsignal can be efficiently transmitted and received using complex numberrepresentation. The I and Q components allow for more efficient use ofthe available bandwidth, as they can transmit multiple bits ofinformation per symbol, enabling higher data rates. The combination of Iand Q components also facilitates the demodulation process, allowing theoriginal signal to be accurately recovered at the receiver end.

The modulated signals (I and Q components) are coupled to a DSSSmodulator 440, where DSSS stands for Direct Sequence Spread Spectrum.This modulator 440 takes the original data signal and combines it with aspreading code to generate a spread spectrum signal. Depending onimplementation, the DSSS modulator 440 may also include other componentssuch as a carrier frequency generator and filters 442 to shape thetransmitted signal. DSSS is a modulation technique, known to thoseskilled in the art, used in wireless communication systems to improvethe reliability and security of data transmission. It achieves this byspreading the signal across a wider bandwidth than necessary for thetransmission of the original data. In DSSS, the data to be transmittedis multiplied by a spreading code, which is a pseudorandom binarysequence (PRBS) of 1s and 0s. This spreading code has a much higher datarate than the original data, effectively spreading the signal over awider frequency band. The resulting spread spectrum signal has a lowerpower spectral density, meaning it occupies a larger frequency bandwidthcompared to the original signal. DSSS is commonly used in variouswireless communication standards, including Wi-Fi (IEEE 802.11b) andBluetooth, to provide robust and secure data transmission in noisy orcrowded environments.

The outputs from the DSSS modulator 440 are coupled to one or more DAC444 (Digital-to-Analog Converter). It is an electronic device or circuitthat converts digital signals into analog signals. The analog signalsfrom the DAC 444 are mixed in a mixer 445 (e.g., I/Q mixer) with asignal of a different frequency from a local oscillator (LO) 446.

An I/Q mixer, also known as a quadrature mixer or a complex mixer, is atype of mixer used in electronics and communications systems to convertsignals between the analog and digital domains, where I and Q in I/Qstand for In-phase and Quadrature, respectively. The main purpose of theI/Q mixer 445 is to shift the frequency of the input signals. Itachieves this by multiplying the I and Q signals with the LO signal. Themultiplication process involves combining the two input signals with theLO signal, resulting in sum and difference frequencies being generated.

One of the important advantages, benefits and objects in the presentinvention is the generation of the LO signal from the local oscillator446. According to one embodiment, at least two optical sources 448 areused to initially generate optical signals. In one embodiment, two IRlaser diodes are used to generate infrared signals, a type of laser thatemits light in the infrared portion of the electromagnetic spectrum.Infrared light has longer wavelengths than visible light, ranging fromapproximately 700 nanometers (nm) to 1 millimeter (mm), beyond the rangeof human vision.

The optical signals are projected onto a photo mixer 450, also referredto as a terahertz photo mixer, a device used for generating or detectingterahertz (THz) radiation, typically between 0.1 and 10 THz,corresponding to wavelengths in the range of 30 micrometers to 3millimeters. In operation, two optical beams from the laser source 448are directed onto a photoconductive material. One beam acts as a pumpbeam, typically in the near-infrared or visible range, and the otherbeam is the terahertz signal beam. By applying a voltage bias across thephotoconductive material, a generated terahertz output signal can beamplified and radiated as terahertz radiation. This process is known asterahertz generation or emission. In terahertz detection: the terahertzphoto mixer functions as a terahertz detector. The terahertz signal isincident on the photoconductive material, generating a time-varyingcurrent. This current can be amplified and processed to extract theterahertz signal information.

The outputs (e.g., ω1+ω1, and ω1−ω1) from the photo mixer 450 arecoupled to a lowpass filter 452 to produce signals with only wantedfrequencies (e.g., 300 GHz). The signals are provided to the oscillator446 to generate a repetitive waveform or signal with a specificfrequency and amplitude in different shapes, such as sinusoidal, square,triangular, or sawtooth, depending on implementation.

The output from the photo mixer 450 is further processed in a band-passfilter 454 to pass signals within a specific frequency range whileattenuating or blocking signals outside that range. The filtered outputis then amplified in an amplifier 456 to a predefined level beforereaching a directional coupler 458, where the directional coupler is adevice used to separate or combine power between multiple transmissionlines. It allows for the monitoring, sampling, or coupling of signals ina specific direction while minimizing the impact on the main signalpath. The main signal from the directional coupler 458 are transmittedvia an antenna 460.

The operation of the transceiver 430 on receiving signals is oppositeand substantially similar to the transmitting operation as describedabove. Those skilled in the art shall understand the substantiallyidentical parts and their respective operations in the receiving portion436 given the detailed description above. For completeness, FIG. 4Dshows a functional diagram of another terahertz wireless transceiver 470that may be used in smart XR glasses. The transceiver 470 issubstantially identical to the transceiver 430 of FIG. 4C except a firstantenna 472 is used to transmit wireless signals while a second antenna474 is used to receive wireless signals. In other words, thetransmitting and receiving antennas are two independent antennas.According to one embodiment, the planar antenna 472 is implemented witha thin-film metamaterial transparent antenna.

According to one embodiment, an exemplary thin-film metamaterialtransparent antenna is an antenna structure that incorporatesmetamaterials and substantially transparent to certain frequencies ofelectromagnetic waves. As described above, the planar antenna 472 or 308of FIG. 3A includes conductive materials in very fine size (e.g.,nanometers) that are barely visible when deposed on an integrated lens.The metamaterials are artificially engineered materials that exhibitunique electromagnetic properties not found in naturally occurringmaterials. They are designed to manipulate the behavior ofelectromagnetic waves in ways that are not possible with conventionalmaterials. In one embodiment, the thin-film metamaterial transparentantenna involves integrating metamaterial elements into a thin film orsubstrate material, allowing it to transmit and receive electromagneticwaves while maintaining high transparency. This type of antenna can beparticularly useful in applications where aesthetics and visibility areimportant, such as in transparent windows, displays, or other deviceswhere conventional antennas may be visually obtrusive.

The design and fabrication of thin-film metamaterial transparentantennas may vary depending on the specific requirements and operatingfrequencies. Typically, the antenna structure includes metamaterialelements embedded or patterned into a thin film, which can be made fromvarious transparent materials like glass or plastic. The metamaterialelements are carefully engineered to manipulate the propagation ofelectromagnetic waves and achieve desirable antenna properties such asradiation efficiency, directivity, and impedance matching.

One of the key advantages of thin-film metamaterial transparent antennasis their ability to operate over a wide frequency range whilemaintaining transparency. By tailoring the design parameters of themetamaterial elements, such as their size, shape, and arrangement, it ispossible to create antennas that are transparent to specific frequenciesor frequency bands. This allows for seamless integration of antennasinto transparent surfaces without compromising the overall functionalityor appearance.

Referring now to FIG. 5A, it shows an exemplary configuration 500 inwhich a user 502 is shown to wear a wireless display device 504resembling a pair of reading glasses or sunglasses. According to oneembodiment of the present invention, the device 504 includes twointegrated lenses 506 and 508 that each further include at least onewaveguide that allows an optical image to travel within the waveguide.It should be noted that an optical image is different from an electronicimage or image data. An optical image refers to a visual representationof an object or scene formed by light rays interacting with opticalsystems such as lenses or mirrors while an electronic image or imagedata indicates the signals or data that can be used to display an imagerepresented by the data image/electronic image. In other words, anoptical image is the image formed by actual physical light rays thatenter eyes and cab be captured by an optical device (e.g., lenses orsensors). Technically, an optical image may be considered as an array oflight intensities varying in multiple dimensions (e.g., 2D or 3D).

The device 504 receives image data or other signals over the air orwirelessly via an antenna array (not shown, corresponding to the antenna308 of FIG. 3A) that can be disposed on top of or imbedded in the lens506 or 508. According to one embodiment, the antenna 504 may also bedistributed across the frames or temples of the glasses 504. Accordingto another embodiment, the antenna is disposed on a separate part 510that may be perceived as a balancing unit or balancer, where theseparate part 510 may be used to house circuitry, batteries or etc. andcoupled to the glasses 504 via a pair of cables 512 and 524. Thebalancer 510 is provided to counteract the weight of the device 504 sothat the wearer may feel balanced in weight when wearing the glasses504.

FIG. 5A also shows that the user 502 has a carry-on control device orcontroller 520 (e.g., a smart phone) that communicates with the device504 over the air according to one embodiment of the present invention.It shall be noted to those skilled in the art that the antenna includedin the device 504 is not limited to only communications with thecontroller 520. In one embodiment, the antenna receives image data whilethe user 502 walks near a designated area. The image data may be from aplurality of antennas disposed near the designated area. As the usermoves around in the area, the user can stay connected and enjoy theimmersive experiences.

FIG. 5B shows another embodiment in which the device 504 communicateswith the controller 520 (e.g., iPhone) as well as another controller 522(e.g., Apple Watch). Either one of the controllers 520 and 522 cancontrol the device 504, provide data or cause the device 504 to receivedata from a nearby antenna or designated hotspot(s).

The present invention has been described in sufficient detail with acertain degree of particularity. It is understood to those skilled inthe art that the present disclosure of embodiments has been made by wayof examples only and that numerous changes in the arrangement andcombination of parts may be resorted without departing from the spiritand scope of the invention as claimed. Accordingly, the scope of thepresent invention is defined by the appended claims rather than theforgoing description of embodiments.

I claim:
 1. A system for operating a terahertz transceiver, the systemcomprising: an antenna set; two optical sources generating two opticalbeams at two different frequencies; a photo mixer for generating ordetecting terahertz (THz) radiation, wherein the two optical beams fromthe optical sources are directed onto a photoconductive material, agenerated terahertz output signal is amplified and radiated as theterahertz radiation when applying a voltage bias across thephotoconductive material; a local oscillator receiving the THz radiationand producing a reference signal; and an I/O mixer provided to modulatethe reference signal with a signal or demodulate the reference signal toextract a signal, wherein the signal is transmitted or received via theantenna set.
 2. The system as recited in claim 1, wherein the opticalsources are two laser diodes, and the two optical beams are laser beams.3. The system as recited in claim 2, wherein the antenna set includes afirst antenna and a second antenna, the first antenna and second antennaare in different forms, one for transmission and the other forreception.
 4. The system as recited in claim 3, wherein the signal istransmitted via the first antenna, and the signal is received via thesecond antenna.
 5. The system as recited in claim 4, wherein the secondantenna is a planar antenna disposed on top of an integrated lens in awearable display device.
 6. The system as recited in claim 1, furthercomprising: an interface to transport the signal.
 7. The system asrecited in claim 6, wherein the interface is a USB Type-C.
 8. A methodfor operating a terahertz transceiver, the method comprising: providingan antenna set in a wearable display device; generating from two opticalsources at least two optical beams at two different frequencies;generating or detecting terahertz (THz) radiation in a photo mixer,wherein the two optical beams from the optical sources are directed ontoa photoconductive material, a generated terahertz output signal isamplified and radiated as the terahertz radiation when applying avoltage bias across the photoconductive material; receiving from a localoscillator the THz radiation to produce a reference signal; andmodulating in an I/O mixer the reference signal with a signal ordemodulate the reference signal to extract a signal, wherein the signalis transmitted or received via the antenna set.
 9. The method as recitedin claim 8, wherein the optical sources are two laser diodes, and thetwo optical beams are laser beams.
 10. The method as recited in claim 9,wherein the antenna set includes a first antenna and a second antenna,the first antenna and second antenna are in different forms, one fortransmission and the other for reception.
 11. The method as recited inclaim 10, wherein the signal is transmitted via the first antenna, andthe signal is received via the second antenna.
 12. The method as recitedin claim 11, wherein the second antenna is a planar antenna disposed ontop of an integrated lens in a wearable display device.
 13. The methodas recited in claim 8, further comprising: transporting or receiving thesignal to or from an interface.
 14. The method as recited in claim 13,wherein the interface is a USB Type-C.